Electronic counter



Sept. 18, 1951 s. HANSEN ELECTRONIC COUNTER Filed Dec. 5, 1947 Fiigi.

TO POWER SU PPLY.

Inventor": 65 siecgFried Hansen, by Wig/W 12.

His Attorney.

Patented Sept. 18, 1951 ELECTRONIC COUNTER Siegfried Hansen, LosAngeles, Calif., assignor to General Electric Company, a corporation ofNew York Application December 5, 1947, Serial No. 789,794

4 Claims. 1

This invention. relates to. electronic counters utilizing. electron beamdevices of the multipleanode type.

An. object of thisinvention is to provide a new and improved.lelectronic counter.

Another object is toprovide animproved. electronic counter which is.capable of counting electric pulses. at rates up to 106 pulses persecond.

.A further object is to provide an improved electronic counter which.has a greatly reduced number of, components compared to conventionalcounting circuits.

Another object. is to provide an improved, electronic counter which. isespecially adapted for use-as. a timing. generator for televisionsystems, and for. other purposes.

In. this, invention, there. is provided an electron beam. device ofthecathode-ray type which has: a. multiple-anode. structure hereinafterdescribed, and. an electric. circuit connected to beamedeflecting platesin. the. electron beam, device whichcontrols. the lateral movement. ofthe electron beam from one, anode to, another responsive. tov the pulsescountedso that a counting, ratio is obtained. which depends, solely upontheconstruction. of the multiple anode. structure. In. thepreferredembodiment, the anodestructure comprises a plurality of.parallel anodes arranged in a row substantiall parallelto the directionof the electronbeam... The. anodes on. each. end. of l the row function.as reversing. e1ectrodes,,while those in between. serve as. countingelectrodes. All of the anodes are of material having a secondaryemission ratio substantially greater than one. The controlling circuitcomprisesa flip-flop,

or switching, circuit so. connected to the reversing electrodes thatwhen either electrode is struck by the electron beam, the secondaryemission current produced triggers the switching circuit which, in turn,effects a reversal in polarity ofthe voltage between beam deflectingplates of the electron-beam device: Since the polarity of voltagebetween the deflecting plates determines the direction of-fl'ateralmovement of the electron beam,'the electron beam reverses its direc tionof lateral movement: each time a predetermined number of pulsesiscounted and-the electron beam arrives at" one of the end anodes. Forexample", fivecounting electrodes may be-providedg which makes a total fseven anodes including the two: reversing electrodes. As pulses arecounted, the electron beam moves fromthe first to: the fifth countingelectrode; and" then to one oi the reversing electrodes. Thereupon thevoltage between deflecting plates is: reversed in polarity, and the beamretraces its path in the opposite direction until; it reaches the. otherreversing electrode; In completing a full cycle on operations, the beampasses over each count.- inge'lectrodetwice. Therefore; the countingratio is two times the number of electrodes, or. 10:1 in the examplegiven. This counting ratio. may be increased by simply adding morecountingelectrodes. Thus, a. high counting ratio with, relatively fewcomponents is possible. The reversing electrodes not. only double the,counting ratio of the device, but also increase the maximum countingspeed, since they make possible. the elim ination of the relatively longtime interval which otherwise would be required to return thebeam tostarting position after it passed the lastcounting electrode.

The features of the invention which. are believed to be. novel andpatentable are set forth inthe appended claims. For a betterunderstanding of the invention referenceismade in the fol.- lowingdescription to. the accompanying drawing, in which Figl is adiagrammatic represents..- tion of one embodiment of the inventiomliig,2 is an illustration of a preferred anode. structure utilized in theelectron. beam device. shown. in Fig. 1, Fig. 3 illustrates amodification of the anode structure of Fig. 2; Fig.4 is an. alternativeanode. structure; and Fig. 5 is a-schematic, d1- agram illustrating, thechanges. necessary to. utilize the anode structureof Fig.4.

Referring now to Fig. 1, an electron-[beam device lil comprisesanenvelope IDA, which con..- tains. an electron emissive cathode H, acontrol grid I2, a pair oiv accelerating. and focussingelectrodes l3and. I4, a pair of deflecting plates l5 and i6, andanelectricallyconductive coating l1. These component partsare similar to those foundin. a conventional cathode ray oscillograph. tube. The fluorescentscreen which is at the large end of the envelope in an oscillograph tubemay be omitted for some applications of the present device,.and may beincluded for others, as. xplained hereinafter. Adjacent to the large endl8 of envelope IDA is an anode structure which comprises a plurality of.parallel. anodes or targets 19, 2|], 2|, 22, 23, 24 and 25. Morespecifically. the targets l9 and 25 will be referred to as reversingelectrodes and the targets 2 ll24 as counting electrodes. Preferably,the exposed surfaces.

of the anodes are constructed of an electrically conductive materialhaving a secondary emission ratio substantially greater than one. Forexample, anodes coated with magnesium oxide or beryllium oxide may beused. The preferred configuration is illustrated in detail in Fig; 2.The number of counting electrodes 20--24 determines the counting ratioof the tube. The end or reversing electrodes l9 and 25 take part: inchanging the direction of the lateral movement of the electron beam asit leaves either electrode Her 24, as-hereinafter explained.

A. conventional power supply, not. shown, connected to. terminals 26'furnishes the required voltages for operation of the" electron beamdeknown to those skilled in the art pertaining to cathode rayoscillograph tubes and similar electron-beam devices.

In the embodiment illustrated in Fig. 1, a source of negative pulses tobe counted is connected to input terminals 21. The negative pulses aretransmitted through coupling capacitor 28 to control grid l2. Pulses tobe counted should have an amplitude large enough to drive control gridl2 sufiiciently negative to momentarily interrupt the electron beam.

Potentials for controlling the lateral movement of the, electron beamare supplied to the deflect: ing plates l5 and I6 by a voltage-controlcircuit 29. which comprises two amplifiers which respectively includevacuum tubes 30 and 3!. Tube 36 comprises a cathode. 32, a control grid33, a screen grid 34, a suppressor grid 35 which is connected to cathode32, and an anode 36. Tube 3| is similar to tube 30,and comprises acathode 31, a controlgrid 38, a-screen grid 39. a suppressor grid 40connected to cathode 31, and an anode 4|. Both cathodes are connected toa common ground terminal 42. Anode voltage for tubes 30and 3| issupplied through resistance networks 46jand 41 from a conventionaldirect current supply circuit,.not shown, which has its positiveterminalconnected to terminal 43 and its negative terminal connected toground. The potentials of anodes 4| and 36 are appied to deflectingplates l5 and [6, respectively, through connections 44 and 45.

Tubes 30 and 3| are caused to operate alternately under'the control of aflip-flop circuit 48. This flip-flop circuit comprises a pair ofelectron discharge tubes 49 and 56 having, respectively, cathodes 5| and52, control grids 53 and 54, and anodes 55 and 56. Anode voltages fortubes 43 and 50 are supplied from terminal 43 through the respectiveresistance networks 46 and 41. These tubes function as switching devicesunder the control of the reversing electrodes [9 and 25, as explainedhereinafter. The reversing electrodes l9 and 25 are connected,respectively, by a pair of conductors 51 and 58 to the control grids 53and 54. A resistance network 59 comprises two resistors 60 and GI offixed value and a resistor 62 .which is connected between thefirst-mentioned resistors. All three resistors 66-62 are connected inseries between the control grids 53 and 54. Resistor 62 is provided withan adjustable tap 63 connected through a resistor 65 and adjustable tap66 to terminal 64, to which a source of negative bias voltage, notshown, is connected. .Tap 66 provides means to adjust, simultaneously,the bias voltage applied to the grids 53 and 54, and tap '63 is used toadjust the relative bias voltages'applied to the two grids. Terminal 64is also utilized to supply a bias voltage to grids v 33 and 38, and isconnected to these grids through a conductor 61 and resistor 68. Grids33 and 38 are tiedtogether and connected by a conductor 69 to thecounting electrodes 2024.

Fig. 2 illustrates the preferred structure of anodes l9-25. The exposedsurfaces of these electrodes are made of a material, beryllium oxide forexample, capable of producing secondary .emission currents when struckby the electron beam. The reversing'electrodes l9 and 25 are suitablysupported within envelope IllA,.and are insulated from each other andfrom the counting electrodes. The counting electrodes Ell -24 may bestamped out of a Single piece of material in the form of a grid 20Ahavin any desired number of parallel strips (26-24), depending on thecounting ratio desired as will be presently explained. The illustratedconstruction of the counting electrodes permits theme of very simple andstraightforward supporting means, which provides a decided economy inthe manufacture of such devices. Obviously, the electron receivingelectrodes could be simplified further by utilizing a metallicconducting paint, applied, for example, on an insulating material suchas glass. The conducting material must, of course, have a secondaryemission ratio substantially greater than one. Electrons which strikethe insulating material build up a small surface chargethereon. Thisraises the potential of the insulating sur: face a few volts, but notenough to substantially alter the path of the electron beam. The smallrise in potential, however, is sufiicient to increase the secondaryemission ratio of the insulating material to one, so that thereafter anequilibrium exists between the number of electrons arriving at theinsulating surface and those leaving due to secondary emission. Theelectrons which are emitted travel to coating ll. 7

In Fig. 3 is illustrated a plurality of electronreceiving electrodes13A, 26B and 25A arranged to be disposed on the inner surface of theportion It of the envelope IDA by vacuum evaporation of a metal, such asaluminum or silver. The

' proper electrode pattern can be arranged by making this disposition ofthe material through a mask designed in accordance, for example, withthe electrodes illustrated in Figs. 2 and 4. Subsequently, its secondaryemission ratio could be substantially increased by the evaporationthrough the same mask, of an extremely thin film of magnesium (Mg) orberyllium (Be), and this film, in turn, oxidized by'baking in air toproduce a surface having a thin film of. MgO or BeO. Such a surfacegives a high secondary emission yield. The ratio of this emission to theprimary emission being substantially greater than one.

Referring to Fig. 1, assume that tube 30 is conducting and that thepotential of grid 33 is such that the electron beam is directed into thespace between electrodes l9 and 26. As a result, no current flows toelectrode 20 and the grid 33 of the tube 30 is rapidly driven morenegative 'as' the wiring and electrode capacitances discharge throughresistor 68. As grid 33 becomes more negative, anode 36 becomes morepositive;

' and since deflecting plate I6 is connected to'the anode 36, aright-hand deflection (with respect to the observer) of the electronbeam occurs. This deflection continues until the beam strikes thecounting electrode 20. If the entire crosssection of the beam shouldstrike. electrode 26', a secondary emission current would be set upwhich is more than sufiicient to counteract the discharge of circuitcr-pacitances through resistor 68, and thus tends to drive grid 33rmorepositive and deflects the electron beam to the left. As a 7 result, anautomatic servo action exists which so interrupts the secondary-emissioncurrent. During this interruption, discharge of the circuit I causes thebeam to come torest partly on and partly ofi electrode 20, in such a waythat the secondary emission current is substantially equal to thecurrent through resistor 68. The electron beam then remains on the leftedge of counting electrode 20 until an impulse of negative polarityarrives at the input circuit 21. This negative impulse momentarilyinterrupts the electron beam by driving control grid l2 to cut-oil, and

aaeeguo capacitances. through resistor Bills resumedtso that at the endof the input pulse the electron beam: is reestablished on a path whichis to the right; of electrode: 20, and: which may pass between.electrodes and. 21 if the input pulse is of thaproper duration. The beamthus travels to the left edge of electrode 2 whereupon secondaryemission current arrests the laterali movement'. A tolerance of theorder of plusior minus 50% in. the duration of: the input impulse is.al-

lowable; sinceif the electron beam falls anywhere in the spaces betweenthe electrodes: or on. them, it: willi automatically seek tow the leftedge: of the electrode. This relatively large tolerance of adjustment isone of the principal advantages of this counting system over thepreviously used chains of multi -vibrators used in radar" or'tel'evisiontiming generators.

The electron beam progresses from. one countting electrode to the nextin response to: each i negative impulse arriving at the in ut. circuit211, This progression continues until the" last electrode 24- is passed;whereupon the electron beam strikes the right-hand reversing electrode25". The flow of secondary emission currentfrom this last-mentionedelectrode applies a positive impulse to grid 53 of tube l9 and transferscurrent from. tube 50' to tube 49* by the: switching action offlip-fiopcircuit 48. This reduces the potentials applied to screen grid 34 andanode 36. and raises the potentials applied to screen grid 39 and anode41. When this-occurs, tube becomesnonconductingand tube 31 assumescontrol of the electron beam deflection. When this switching actionoccurs there is atendency to If deflect the electron beam rapidly to theleft. However, capacitances' of the wiring and the defleeting platesprevent thebeam being deflected instantaneously to the left side of theanode structure; therefore, the beam in moving to the left strikes anode24-, and produces a secondary emission current sufficient to arrestfurther deflection to the left. The beam may be deflected back into thespace between anodes M and 25-for an instant due to sudll'enover-correction. From a symmetry conditions it is evident" that thecounting tube It] will now perform just as before except that theelectron beam will progress from right to left. The arrival of negativeimpulses at input 21 will cause the beam to jump from one countingelectrode-to the next until it reaches the left reversing electrode F9whereupon the flip-flop circuit again operates to restor'e the initialconditions.

It is evident that in completing a full cycle of operations the beamwill pass over each counting electrode (20-24) twice and, therefore, thecounting ratio is twice the number of counting electrodes or tento onefor the structure shown in Fig. 2. This ratio may be increased to1'000to l, for example, by simply adding more counting electrodes. This highcounting ratio with relatively few components is another advantageoflthe' invention.

The countingspeed. is limitedv only by the rate of discharge of circuitcapacitances through-resi'stor 68 and by the reversal time. of fii'pflop circuit 48 With this present invention it is possible-to countimpulses of the order of 5 1 0 per second. If a slower counting speed.is desired for longer impulses, it is only necessary to add a capacitorH!- of appropriate"-value between ground and conductor 69 to reduce therate of discharge of circuit capacitances through resistor 68.

envelope MA a fluorescent screen at the large end: t8 of the envelope toindicate the position of the electronnbeam. If it is desirable toreset'the system to zero before a count is made, this can be done bymomentarily biasing the deflection plates through: asuitable circuit tothat voltage which will: cause the beam to fall on the lefthandreversing electrode l9; When. this: biastis released, the system will bein the initialeondition.

The counter illustrated in Figs. 1 and 2 provides means :for counting:pulses of substantially uni"- form duration and either uniform or randomrepetition rate. In order to count impulses having random duration, itis preferable to use a counter having an anodestructure' as illustratedin Fig; .4. Referring now to Fig; 4, a counting electrode structure I I-A comprises a plurality of anodes TI to 19, inclusive; arranged in twointerleavedrows in the form of a grid in which the unattached ends ofthe electrodes 72-, 'M, 7'8, and 18' extend into the'spacesformed' bythe unattached ends of the electrodes TI, l3, 15, 1'1 and 19. A pair ofreversing electrodes 80 and 8| are provided at-th'e opposite ends of"the anode structure, and operate in the same manner as thereversing'el'eotrodes I 9 and 25' of Fig; 1. The anodes may beconstructed as described in connection with electrodes I9-25 or they maWe constructedasiillustrated in Fig. 3. 1

When the counting electrode structure! this utilized, the electron beamdevice It must incorporate, as illustrated in Fl'g; 5 an second pair ofdeflecting plates82 and 83; These plates provide the means, whensuitably energized; to deflectthe electron beam perpendicular to: thedirection of deflection; provided by plates l5 and It. InrelationtotFig; 5;.p1'ates it-and lfi-deflect'theelectron beam vertically, andplates 82 and 83 deflect the electron beam perpendicular to the plane ofthe drawing. Terminals 84 are provided for connecting the source ofpulses counted to deflecting plates 82 and 83-, rather than to thecontrol gri'dtas in- Fig. 1'. Terminals at andian adjustable tarosisto'r"86" are provided for connecting to plates 82 and 83 a suitableDL-C. source, not shown, to provide proper operating potential to thesedeflecting plates. otherwise; the apparatus is similar tothatillustratied in Fig. 1.

The operation of the apparatusishown in Figs. 4

and 5 is essentially the same as described in connection with theembodiment of'the invention itlus-trated': in Figs. 1 and 2Forexample-referring to Fig. 4, assume that an electron beam A isresting on the left edge of electrode H and that' the bias on thevertical plates ti -83 is arranged so where it-Wflli remain until thearrival of theinext impulse at input 84.

The positioning of the electron beam substantially between points B andC, Fig. 4, may be ac- "complished by adjusting the direct currentpotential applied to deflecting plates 82 and83 by adjusting the tapposition on resistor 86; while positioning of the electron beam betweenpoints D and E is accomplished by limiting the amplitude of the impulsesignal applied to the input circuit 84. Means for amplitude limiting iswellknown in the art and is therefore omitted from the presentdescription.

The utilization of the electrode structure of Fig.1 4 in combinationwith the circuit above described enables one to count impulses of randomduration and random interval such as occur in nuclear disintegration.

Other arrangements for utilizing the present invention'maysuggestthemselves. For example,

Qarrangement would alternately cause the electron beam to move frommidway between B and 'C to midway between D and E and so on, inaccordance with the impulses applied to the flipflop circuit.

' The embodiments of the present invention which have been illustratedand described have been selected for the purpose of setting forth theprinciples involved. It will be obvious that the invention may bemodified to meet various con: ditions for difierent specific uses anditis, therefore, intended to cover by the appended claims all suchmodifications which fall within the spirit and scope of this invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. Apparatus for counting electric pulses, comprising means to form anelectron beam, an anode structure includin a plurality of countingelectrodes, beam deflecting means, voltage control means connected tothe deflecting means to apply thereto a deflecting voltage of variablemagnitude to cause the electron beam to move laterally from one countingelectrode to another responsive to the electric pulses counted, thevoltage control means being connected to the counting electrodes andresponsive to electric current flowing thereto to arrest lateralmovement of the electron'beam between the pulses counted, reversingelectrodes at respective ends of the anode structure, a flipflop circuithaving respective input triggering terminals connected to saidreversingelectrodes and having output terminals connected to the voltage controlmeans, so that whenever the electron beam strikes one of the reversingelectrodes the flip-flop circuit is triggered and thereby reverses thepolarity of voltage applied to the beam deflect ing means, whereby thedirection of lateral movement of the electron beam is reversed.

2. Apparatus for counting electric pulses, comprising meansto form anelectron beam, an anode structure including a plurality of countingelectrodes, beam deflecting means, voltage control means to control themagnitude of voltage applied to the deflecting means, said voltagecontrol.

means being connected to the counting electrodes and responsive toelectric current flowing thereto 7 to cause lateral movement of theelectron beam file of this patent:

3. Apparatus for counting electric pulses, com-'- 7 prising means toform an electron beam, an anode structure including a plurality ofcounting electrodes arranged in two interleaved rows, first deflectingmeans to move the electron beam laterally from one counting electrode toanother in the same row, voltage-control means connected to thecountingelectrodes and responsive to current flow thereto to arrest suchmovement, second deflecting means to move the electron beam from one rowto the other, input terminals'for the pulses to be counted, and aflip-flop circuit having triggerin terminals connected to said inputterminals and output terminals connected to said second deflectingmeans, so that electric pulses applied to the input terminals triggerthe flipflop circuit, thus reversing the polarity of voltage applied tothe second deflecting means and moving the electron beam from one row ofcounting electrodes to the other, whereby the electron'beam'beam-deflecting plates arranged on opposite sides of the electron beamto deflect the beam from one counting electrode to another, twoamplifiers having their output terminals connected to respective ones ofthe deflecting plates and their input terminals connected together andto the counting electrodes, a flip-flop circuit connected to bias tocut-ofi one-or the other of the two amplifiers selectively, saidflip-flop circuit having respective triggering terminals connected tothe reversing electrodes, a control grid positioned in the path of theelectron beam, and input terminals for the pulses to be countedconnected to said control grid. r I

SIEGFRIED HANSEN REFERENCES CITED 7 V The following references are ofrecord in the UNITED STATES PATENTS 2,446,945 Morton et al Aug. 10, 1948

